Rotary eccentric fluid motor

ABSTRACT

An internal gear type fluid motor comprising an inner gear member mounted stationary and an outer gear or internally toothed member mounted for orbital movement about the stationary inner gear in response to pressure fluid being introduced into the expansible chambers formed by the cooperating gear members. The outer gear member is mounted in a housing which itself is mounted for rotation about an axis in response to the orbital movement of the outer gear member. The housing includes a cam surface which provides an eccentric drive for a hydraulic percussion mechanism. The fluid motor and percussion mechanism are mounted in a tool housing in such a way that the percussion mechanism receives hydraulic fluid discharged from the fluid motor.

United States Patent [1 1 Strecker et a1.

l l 3,862,813 1 Jan. 28, 1975 ROTARY ECCENTRIC FLUID MOTOR [73] Assignee: Gardner-Denver Company, Quincy,

[22] Filed: Nov. 1, 1973 [2]] Appl. No.: 411,967

Related U.S. Application Data [62] Division of Ser. No. 270,777, July 11, 1972, Pat. No.

Primary Examiner-John J. Vrablik Attorney, Agent, or Firm-Michael E. Martin [57] ABSTRACT An internal gear type fluid motor comprising an inner gear member mounted stationary and an outer gear or internally toothed member mounted for orbital movement about the stationary inner gear in response to pressure fluid being introduced into the expansible chambers formed by the cooperating gear members. The outer gear member is mounted in a housing which itself is mounted for rotation about an axis in response to the orbital movement of the outer gear member. The housing includes a cam surface which provides an eccentric drive for a hydraulic percussion mechanism. The fluid motor and percussion mechanism are mounted in a tool housing in such a way that the percussion mechanism receives hydraulic fluid discharged from the fluid motor.

5 Claims, 7 Drawing Figures ROTARY ECCENTRIC FLUID MOTOR This is a division of application Ser. No. 270,777, filed July 11, 1972, now US. Pat. No. 3,791,149.

BACKGROUND OF THE INVENTION Fluid pumps and motors of the so-called internal gear type are well known and are generally characterized by an inner gear member having a plurality of external teeth which cooperate with an outer gear member having internal teeth to form expansible chambers. The internal gear is usually formed with one less tooth than the outer gear member and the centers or axes of the tooth outlines of the respective members are spaced apart and parallel. Various arrangements of mounting the inner and outer gear members are known to provide for rotary or orbital movement of one or both members; however, for application as motors such devices are usually arranged to provide for the inner gear to be mounted on a rotatable shaft which may rotate about a fixed axis. Internal gear type motors are also known in which the inner gear moves in an orbital manner as well as rotating about its own center axis.

For certain applications of the general type of fluid motor discussed hereinabove, it is desirable to produce an eccentric type of motion as well as to provide for a sizeable rotating rnass whereby a flywheel effect or considerable inertia can be utilized to drive an associated mechanism. Moreover, in certain types of fluid operated mechanisms it is desirable to be able to utilize a common source of working fluid and to make the complete device using the fluid motor as compact and mechanically simple as possible.

SUMMARY OF THE INVENTION The present invention provides for a fluid motor of the internal gear type wherein an inner gear member having a plurality of external teeth is fixedly mounted so that a cooperating outer gear member responds to the introduction of pressure fluid admitted to expansible chambers formed by the cooperating gear teeth to orbit about the inner gear member to thereby produce rotary motion. In the fluid motor of the present invention the outer gear member is mounted in a housing which includes bearing means for supporting the outer gear member and which is mounted for rotation in response to orbital movement of the outer gear member.

The present invention also provides an internal gear type fluid motor in which the orbital movement of the outer gear member is converted to rotary movement of a rotatably mounted motor housing which includes a cam surface for providing eccentric type motion. With the internal gear type motor of the present invention a substantial rotating mass is provided by rotatably driving the motor housing whereby a substantial flywheel effect is produced by the rotational inertia of the housing and outer gear member.

The present invention further provides for an improved hydraulic percussion tool characterized by a piston which is reciprocably driven by an internal gear type motor having an eccentric formed by a rotating motor housing. In the hydraulic percussion tool of the present invention an improved internal gear type fluid motor having a fixed inner gear is operable to directly drive a reciprocable fluid displacing piston by an eccentric formed by the motor housing itself. Accordingly, a compact and positive drive mechanism is thereby provided. Moreover, the hydraulic percussion tool of the present invention advantageously utilizes hydraulic fluid from a common source for driving the internal gear motor and the hydraulic percussion mechanism. The hydraulic percussion tool according to the present invention is more compact and reliable than heretofore known devices of the general type disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal section view of a hydraulic percussion tool including an internal gear type fluid motor in accordance with the present invention.

FIG. 2 is a view taken along the line 22 of FIG. 1.

FIG. 3 is a view taken along the line 3-3 of FIG. 2.

FIGS. 4 through 7 are detail views showing in sequence a complete revolution of the motor housing at intervals of degrees of rotation.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 of the drawing a hydraulic percussion apparatus is shown and generally designated by the numeral 10. The apparatus 10 includes a housing 12 having an interior bore 14 forming a chamber 15. The bore 14 includes an enlarged diameter portion 16 in which is retained a circular flanged portion 18 of a cylinder housing 20. The cylinder housing 20 includes a flanged portion 22 at its opposite end which is sealingly fitted in the housing bore 14 by means of an O- ring 24. The cylinder housing 20 includes a longitudinal bore 26 forming a first cylinder and a reduced diameter bore portion 28 forming a second cylinder in communication with the bore 26. Transverse passages 30 connect the reduced diameter bore 28 with the chamber 15. A hollow fluid drive piston 32 is slidably disposed in the bore 26 and is engageable with a coil spring member 34 disposed in the bore also. The drive piston 32 includes a head portion comprising a movable valve member 36 which is disposed to close one end 38 of the piston and is engageable with the spring 34. The member 36 includes a transverse surface 40 and includes also plural radially extending guides 42 for guiding the movement of the member within the piston 32 and also forming therebetween passages for admitting pressure fluid to the bore 26 from a chamber 27 formed above the flanged portion 18. The last mentioned function of the member 36 may be performed when the spring 34 has biased the member into an open position with respect to the end 38 of the piston 32 as shown in FIGS. 5 and 6.

The apparatus 10 also includes an impact piston 44 reciprocably disposed in a chamber 46 formed in the housing 12. The impact piston 44 includes a portion 50 which is operable to deliver impact blows to a blowreceiving member 52 removably retained in a 'sleeve 54 by suitable retaining means 56. The impact piston 44 includes an integral reduced diameter portion 58 disposed in the bore 28 and sealingly engaged with a suitable fluid seal 60 to prevent communication of the bore 28 with chamber 46. The impact piston 44 also includes a resilient annular seal member 62 commonly known as a U-cup seal which is operable to valve fluid trapped in the chamber 46 around the periphery of the piston into the chamber portion 47 in response to movement of the piston 44 toward the flanged portion 22. The seal 62 is effective to prevent fluid, such as air, from being admitted to the chamber 46 during movement of the piston 44 toward the blow-receiving memher 52. In this way the chamber 46 is usually evacuated and forms a vacuum chamber for biasing the piston 44 toward the cylinder 20. The piston 44 also is cushioned from striking the wall 48 by a pneumatic cushion formed in chamber 47 by closure of a plurality of longitudinal grooves 64 on the piston portion 50 upon entry of the entire groove length into the bore 66. The percussion mechanism of the apparatus formed by the pistons 32 and 44 and their associated cylinders is essentially of the same type as disclosed in US. Pat. No. 3,140,586 to K. E. A. Joelson and reference may be had to the Joelson patent for a description of the general operation of the mechanism and of the advantages thereof. Generally, the apparatus 10 operates to drive the impact piston 44 to deliver blows to the member 52 by trapping hydraulic fluid in the bore 26 and accelerating the drive piston 32 toward the impact piston 44 with the member 36 closed over the end 38 of the drive piston. Displacement of the fluid trapped in the bores 26, 28 will act on the distal end of the piston portion 58 forcing the piston 44 at high speed toward the member 52 until the passages 30 are uncovered by the end of the piston portion 58. Any fluid remaining to be displaced from bores 26 and 28 will then be vented into chamber 15. The piston 44 will be returned by the operation of the vacuum chamber 46 for repetition of the blow-delivering cycle which is initiated by means described hereinbelow.

Referring to FIGS. 1, 2 and 3 the apparatus 10 includes a rotary pressure fluid motor generally designated by the numeral 70. The fluid motor 70 is substantially enclosed by a casing 72 suitably fastened to the housing 12 and including a removable cover member 74. The motor 70 also includes a stationary shaft 76 mounted in the casing 72 and fixed against rotation with respect to the casing by keys 78 interfitted between the casing and the shaft. The shaft 76 is also fitted at the opposite end in the cover member 74. A longitudinal passage 80 in the shaft opens to one end and is in communication with a fluid inlet port 82 in the cover member 74. The motor 70 is further characterized by an inner gearlike member 84 which is mounted stationary on the shaft 76 by means of suitable keys 86. The gear member 84 may also, of course, be made integral with the shaft. The gear member 84 has a plurality of radially projecting external lobes or teeth 88 and has a center axis designated by numeral 90 which is coincident with the longitudinal center axis of the shaft 76. An outer gear member 92 having radially inwardly projecting internal lobes or teeth 97 is disposed in surrounding and interengaging relationship with the gear 84 and has a center axis at 94 which is also the center of the gear outer circumference 96. The axes 90 and 94 are spaced apart but substantially parallel. The gears 84 and 92 shown in the drawings have six and seven lobes or teeth, respectively, although other combinations of numbers of teeth are well known. The outer surrounding gear such as the gear 92 has at least one more tooth than the gear 84 in order to form a plurality of axially open ended expansible chambers such as the chambers 98 and 99, FIG. 2. The gears 84 and 92 are cooperable to operate as pumps and motors in a number of well known ways as disclosed for example in US. Pat. Nos. 3,127,483 to R. W. Brundage and 3,39l,608 to M. J. I-Iuber.

The gear 92 is disposed within a bearing means comprising a cylindrical bore 100 formed in a motor housing member 102. The housing member 102 includes an outer circular cam surface 104 engaged with the surface 40 of the valve member 36, the latter acting as a cam follower. The center axis of the cam surface 104 is located at 106, FIG. 2. Holes 103 are formed in the housing member 102 to reduce the effect of centrifugal forces. These holes may be eliminated for certain applications where unbalanced forces may be desirably utilized. The motor housing member 102 is disposed between two opposed end plates 108 and 110 which respectively include integral stub shaft portions 112 and 114. The end plates 108 and 110, which form end walls for closing the axially open ended chambers 98 and 99, are fastened together and to the housing member 102 by suitable screw type fasteners 116. The shaft portions 112 and 114 are rotatably mounted in bearings 118, disposed in the cover member 74 and the casing 72, and surround the stationary shaft 76. The motor housing formed by the members 102, 108, and 110 is rotatable about an axis which is coincident with the center axis 90 of the gear 84 and the shaft 76. The housing members 108 and 110 could also be rotatably supported by the shaft 76. Since the axis 106 of the cam surface 104 is spaced from the axis of rotation of the motor housing an eccentric is formed by the motor housing member 102 which is operable to reciprocably drive the piston 32 by its associated valve member 36 in response to rotation of the motor housing.

The motor housing plate 108 is provided with a circumferential passage 120 surrounding the shaft and in constant communication with the passage in the shaft by way of transverse passages 122. The plate 108 also includes recesslike fluid inlet and discharge ports 124 and 126 respectively which are operable to be in communication with the expansible chambers formed by the interengaged gears 84 and 92. A passage 128 connects the inlet port 124 to the circumferential passage 120. The discharge port 126 includes a passage 132 opening into the interior chamber 27 of the casing 72. The plate 110 also has ports 134 and 136 corresponding to the ports 124 and 126 to provide for elimination of any axial force imbalance due to pressure fluid acting on the sides of the gears 84 and 92.

Contrary to the operation of prior art motors using internal gear sets like the gears 84 and 92, the motor 70 is responsive to the admission of pressure fluid through the inlet port 82 and passages 80, 122, 120 and 128 to port 124 to act on the gears 84 and 92 to cause the gear 92 to orbit and rotate with respect to the gear 84. Referring to FIGS. 4 through 7 the positions of the gear 92 and the housing member 102 with respect to the gear 84 are shown at degree intervals of rotation of the motor housing about the axis 90. FIGS. 4 through 7 also show the position of the gear 92 with respect to the gear 84 at 90 degree intervals as the gear 92 makes one orbit of its center 94 about the axis 90. The orbital motion of the gear 92 due to a pressure fluid medium such as hydraulic fluid interacting between the teeth of the gears forces the motor housing to rotate due to the fact that the center of the bore which is the center 94 is eccentric or spaced from the axis of rotation 90 of the housing. The movement of the housing member 102 to make one revolution for one orbit of the gear 92 about the gear 84 provides for continuous maintenance of the proper position of the ports 124 and 126 with respect to the moving expansible chambers 98 and 99 formed between the gears. The

gear 92 also rotates with respect to the gear 84 and in one orbit makes a fraction of a revolution which is in inverse proportion to the number of teeth in the gear 92. Thus for the gear 92 seven orbits result in one revolution and accordingly the gear 92 and the housing member 102 rotate relative to each other.

The arrangement of the motor 70 which provides for rotation of the housing member 102, constructed to have the eccentric cam surface 104, results in superior drive means for the percussion mechanism of the apparatus 10. The arrangement of the motor 70 to provide for rotation of the motor housing means comprising the members 102, M18, and 110 results in an eccentric member which has a substantial rotational moment of inertia and thereby acts as a good flywheel. Furthermore. by using a part of the motor housing itself as the eccentric drive member a separate eccentric member driven by a fluid motor is eliminated and a more compact arrangement of the motor 70 in the apparatus is provided. A pressure fluid medium such as hydraulic fluid is supplied to the motor from a suitable source, not shown, through the port 82. Fluid discharged from the motor through passages 132 fills the interior chamber 27 to lubricate the bearings 118 and the cam surfaces 40 and 104. Fluid from the interior of the casing 72 is also admitted into the bore 26 of the percussion mechanism when the valve member 36 opens as shown by the positions of FIGS. 5 and 6.- Excess fluid discharged from the motor 70 and not required by the percussion mechanism may be conducted through passages 137 into chamber and out of the apparatus 10 through port 138 along with fluid expelled from the chamber 28 through passages 30.

The operation of the apparatus 10 is made possible by the introduction of high pressure fluid to the inlet port 82 whence fluid flows to the port 124 in the plate 108 by way of passages 80, 122, 120 and 128. Referring to FIGS. 4 through 7, with pressure fluid admitted to the motor 70 as above described the gear 92 will react to pressure fluid in the chambers formed between the gears 34 and 92 in communication with port 124 to move its center 94 in an orbit about the axis 90 in the direction of the arrow 140. The orbital movement of the gear 92 will cause the rotation of the motor housing member 102 about the axis 90 also in the direction of the arrow 140. As the motor housing member 102 rotates from the position of FIG. 4 to FIG. 5 spring 34 will move the valve member 36 to open with respect to the drive piston 32 whereby pressure fluid may begin to flow into the bore 26 from the interior chamber 27 of the casing 72. As the motor housing continues to rotate in response to orbital movement of gear 92 to the position of FIG. 6 the valve member 36 remains open with respect to the piston 32 and the spring 34 engages the piston to move it to its extreme uppermost position as fluid from the interior of casing 72 fills the bores 26 and 28 and the impact piston 44 is biased into is uppermost position toward the flanged end portion 22.

The continued orbital movement of gear 92 in response to the respective filling and emptying of the progressively moving chambers 98 and 99 will rotate the motor housing from the position of FIG. 6 through the position shown in FIG. 7 and back to a position like that of FIG. 4. As the motor housing member 102 rotates from the FIG. 6 to the FIG. 7 position the valve member 36 is seated against the end 38 of the piston 32 and the piston is partially displaced in the bore 26 to drive the impact piston toward the blow-receiving member 52in accordance with the known way in which the percussion mechanism operates. As the motor housing completes one revolution by moving through the position of FIG. 7 to a position as shown in H6. 4 the displacement of the drive piston is completed.

The operating cycle described above is repeated continuously and smoothly thanks partly to the large rotational mass moment of inertia of the motor housing comprising the member 102, 108 and 110. Moreover, a smooth and continuous flow of fluid through the motor and into the chambers 27 and 15 is provided for use by the percussion mechanism and to cool and lubricate the motor. 1

What is claimed is: 1. A rotary'fluid operated motor comprising: a stationary shaft; an inner gear member mounted stationary on said shaft and having a plurality of radially projecting external lobes; an outer gear member disposed for orbital movement with respect to said inner gear member and having inwardly projecting internal lobes cooperable with said external lobes to form expansible chamber means between said gear members; housing means rotatable with respect to said shaft, said housing means including fluid inlet means for admitting pressure fluid to said chamber means, and said housing means including a housing member having a cylindrical bore having a center axis which is eccentric to the axis of rotation of said housing means, said cylindrical bore forming bearj ing means surrounding said outer gear member for engagement with said outer gear member whereby said housing means is rotated with respect to said shaftin response to orbital movement of said outer gear member.

2. The invention set forth in claim ,1 wherein: said fluid inlet means includes an inlet port disposed in said housing means, passage means in said shaft, and passage means'in said housing means incommunication with said fluid inlet port and said passage means in said shaft for conducting pressure fluid from said passage means in said shaft to said fluid inlet port.

3. The invention set forth in claim 1 wherein: said motor includes a casing including bearing means, and said housing means includes a portion disposed in said bearing means whereby said casing supports said housing means for rotation with respect to said casing. 4. A rotary fluid operated motor comprising: a stationary shaft; 1 an inner gear member mounted stationary on said shaft and having a plurality of radially projecting external lobes; j an outer gear member disposed for orbital movement with respect to said inner gear member and having inwardly projecting internal lobes cooperable with said external lobes to form expansible chamber means between said gear members; housing means disposed around said gear members including fluid inlet means for admitting pressure fluid to said chamber means, said housing means being engaged with said outer gear member for rotation with respect to said shaft in response to the orbital movement of said outer gear member;

5. The invention set forth in claim 4 wherein:

said housing means includes a housing member including said cylindrical bore and said cam surface, said housing member being disposed between opposed end plate members, said end plate members including portions for rotatably 'mounting said housing means for rotation with respect to said shaft.

# a a v 

1. A rotary fluid operated motor comprising: a stationary shaft; an inner gear member mounted stationary on said shaft and having a plurality of radially projecting external lobes; an outer gear member disposed for orbital movement with respect to said inner gear member and having inwardly projecting internal lobes cooperable with said external lobes to form expansible chamber means between said gear members; housing means rotatable with respect to said shaft, said housing means including fluid inlet means for admitting pressure fluid to said chamber means, and said housing means including a housing member having a cylindrical bore having a center axis which is eccentric to the axis of rotation of said housing means, said cylindrical bore forming bearing means surrounding said outer gear member for engagement with said outer gear member whereby said housing means is rotated with respect to said shaft in response to orbital movement of said outer gear member.
 2. The invention set forth in claim 1 wherein: said fluid inlet means includes an inlet port disposed in said housing means, passage means in said shaft, and passage means in said housing means in communication with said fluid inlet port and said passage means in said shaft for conducting pressure fluid from said passage means in said shaft to said fluid inlet port.
 3. The invention set forth in claim 1 wherein: said motor includes a casing including bearing means, and said housing means includes a portion disposed in said bearing means whereby said casing supports said housing means for rotation with respect to said casing.
 4. A rotary fluid operated motor comprising: a stationary shaft; an inner gear member mounted stationary on said shaft and having a plurality of radially projecting external lobes; an outer gear member disposed for orbital movement with respect to said inner gear member and having inwardly projecting internal lobes cooperable with said external lobes to form expansible chamber means between said gear members; housing means disposed around said gear members including fluid inlet means for admitting pressure fluid to said chamber means, said housing means being engaged with said outer gear member for rotation with respect to said shaft in response to the orbital movement of said outer gear member; bearing means for supporting said outer gear member for rotation with respect to said housing means, said bearing means comprising a cylindrical bore in said housing means having a center axis which is eccentric to the axis of rotation of said housing means; and, a cam surface disposed on the exterior of said housing means and forming an eccentric for reciprocably driving an associated cam follower in response to rotation of said housing means.
 5. The invention set forth in claim 4 wherein: said housing means includes a housing member including said cylindrical bore and said cam surface, said housing member being disposed between opposed end plate members, said end plate members including portions for rotatably mounting said housing means for rotation with respect to said shaft. 